A revision of the World Health Organisation psychiatric disability assessment schedule

The burden schizophrenia places on the individual, on the family and on society in general is determined more by the associated disability rather than the manifest symptoms. Therefore, measurement of disability provides a baseline for evaluating change and directing treatment. This research has two main aims. The primary purpose of this study was to develop and validate a contemporary revision of the World Health Organisation-Psychiatric Disability Assessment Schedule (1988). Data used was based on data from the WHO Collaborative Study on Determinants of Outcome of Severe Mental Disorders (Sartorius et al., 1986). The second aim of this study was to develop a methodology for the construction of a psychometrically rigorous instrument. This involved the use of standard, modified and original data checking and analysis techniques and input from content-experts. Results from this process indicated that the criteria and selection of experts is based upon the considered judgement of the researcher that the sum of the advantages of the expert validation process outweigh the disadvantages. This study has two discrete outcomes: The revised DAS can be used to assess disability in schizophrenia, and a gold standard methodology which can be applied during instrument development